1. Field of the Invention.
This invention relates in general to telecommunications, and more particularly to a method and apparatus for providing an interworking unit between ATM networks and IP networks.
2. Description of Related Art.
Today""s wireless systems are inefficient at handling small, frequent data calls and bursty IP traffic and therefor present a challenge in implementing high-speed data services. Existing circuit-switched connections will require more time slots as the number of data users increases. Yet the network and radio capacity required to support such large amounts of bursty traffic would make it uneconomic or impossible to implement.
Third Generation mobile phone networks are an evolutionary step up from today""s Second Generation digital mobile systems. Whereas popular second generation, such as GSM, phones are optimized for voice communication, Third Generation smart phones and communicators will be able to transmit and receive a combination of digital information including speech, pictures, video and various kinds of information content. These technologies will provide users with a personal, mobile, multi-media communications service.
High data traffic, in particular IP traffic, is expected with these advanced services. To accommodate the high traffic demand, a number of factors must be considered in choosing a transport protocol, such as: bandwidth efficiency; quality of service (QoS); speech delay-sensitivity; standardization stability and permitted maximum number of concurrent users. ATM and IP switches are the only two protocols available on the market today.
The new ATM adaptation layer 2 (AAL2) standard is an International Telecommunications Unionxe2x80x94Telecommunications Standardization Sector (ITU-T) standard setting forth a multiplexing scheme in ATM for transporting compressed speech. Accordingly, AAL2 and ATM may be used in implementing the next generation (3G or TGN) cellular access network systems. In an AAL2 based RAN, AAL2 signaling is used for setting up an AAL2 connection from a BS to RNC and RNC to MSC. ITU-T is currently involved in specifying the AAL2 signaling protocol which should be completed very soon. Speech signals received at the BS from a mobile terminal are converted as AAL2 packets and transported in the ATM networks. Since, speech packets are rather small (average of 10 bytes), they are multiplexed with packets from other users in one or more ATM cells in order to attain the maximum bandwidth efficiency. The growth of data applications in a cellular network has necessitated the need for an efficient transport application that is capable of supporting voice, data and video. At present, ATM is the only technology that is capable of offering QoS guarantee to the users for integrated voice, data and video. Based on the stringent requirement for QoS in cellular networks, many network equipment vendors are implementing AAL2 based RAN.
However, rapid growth of IP based applications has given impetus to an IP based cellular access networks. A new multiplexing method in IP, called User Multiplexing in a Real Time Protocol (RTP) Payload Between IP Telephony Gateways, is emerging as an alternative to the AAL2 to transport mobile telephony in the Radio Access Network (RAN) in 3rd Generation cellular network system. This method is disclosed in an Internet Draft entitled xe2x80x9cUser Multiplexing in RTP Payload Between IP Telephony Gateways.xe2x80x9d The method, hereinafter referred to as RTP multiplexing or RTP mux, calls for the multiplexing of a number of speech packets using a two byte mini-header which identifies the user associated with a packet. This mini-header thus allows packets from different users to be assembled into an RTP payload thereby reducing the overhead of RTP/UDP/IP headers.
Another reason for anticipation of IP based cellular access networks is due to QoS integration effort in IP. There are several proposals on how to integrate QoS in IP network being discussed in the Internet Engineering Tack Force (IETF) and industry forums. Proposals such as Diff-serv and MPLS are geared towards integrating QoS provisioning in IP networks. Considering that IP based applications will dominate in cellular networks in near future and data traffic will overtake the voice traffic, an IP based cellular access network is foreseen in near future.
Further more, IP telephony has emerged as a contender to the traditional telecom carriers to provide cost effective solution to long distance telephone calls. The H.323 family of standards that include H.225 and H.245 have given impetus to widespread deployment of IP telephony gateways in Intranets. Session Initiation Protocol (SIP), an IETF standard, also been used for IP telephony applications. These standards allow a call request from System Signaling 7 (SS7) based network is carried within the IP network between IP telephony gateways.
Accordingly, QoS integration in IP networks will enable the real time applications to share the transport medium with best effort data of Internet. Since IP is a natural choice for carrying variable size packets and only a small percentage of traffic would require real time guarantee, it can be easily seen that IP based transport will be the protocol of choice for network operators.
However, both AAL2 and IP protocols have advantages and disadvantages. IP switches and routers are ubiquitous and are the preferred solution as a result of bandwidth efficiency. Nevertheless, the new ATM adaptation layer 2 (AAL2) standard now means that ATM switches can be optimized for delay-sensitive speech and packet data services. Further complicating the problem is the promotion by infrastructure vendors of whatever solution they have available. Thus, future Radio Access Networks(RAN) and Core Networks (CN) could be based on ATM and/or IP. Yet, because the signaling of ATM networks and IP networks is different, these two networks cannot be interconnected.
It can be seen then that there is a need for a gateway unit that will interconnect a ATM (AAL2) based access/core network to an IP based (Mux in RTP) access/core network.
To overcome the limitations in the prior art described above, and to overcome other limitations that will become apparent upon reading and understanding the present specification, the present invention discloses a method and apparatus for providing an interworking unit between ATM networks and IP networks.
The present invention solves the above-described problems by providing a gateway unit that will interconnect a ATM (AAL2) based access/core network to an IP based (Mux in RTP) network.
A system in accordance with the principles of the present invention includes an interface disposed between a first and second network, wherein the first network uses a first type of signaling and the second network uses a second type of signaling, the interface translating signaling between the first and second networks.
Other embodiments of a system in accordance with the principles of the invention may include alternative or optional additional aspects. One such aspect of the present invention is that the first network in an ATM network.
Another aspect of the present invention is that the second network is an IP network.
Another aspect of the present invention is that the first network uses AAL2 signaling.
Another aspect of the present invention is that the interface further includes a control plane for translating signaling between the first and second network.
Another aspect of the present invention is that the interface further includes a user plane for converting user data from the first type of signaling to the second type of signaling.
Another aspect of the present invention is that the control plane maps services between the first and second networks and transfers the services between the first and second networks.
Another aspect of the present invention is that the interface includes at least one interface module and multiplexing module.
Another aspect of the present invention is that the interface module includes a first type of interface module for providing connectivity to the first network and a second type of interface module for providing connectivity to the second network.
Another aspect of the present invention is that the multiplexing modules include a first type of multiplexing module for providing multiplexing and demultiplexing packets for the first type of signaling and a second type of multiplexing module for multiplexing and demultiplexing packets for the second type of signaling.
Another embodiment of the invention includes a method for interfacing between a first and second network, wherein the method includes using a first type of signaling at a first network, using a second type of signaling at a second network and translating signaling between the first and second networks.
Another embodiment of the invention includes a method for providing messaging between a network of a first type and a network of a second type, wherein the method includes setting up a connection between the network of the first type and the network of the second type using an interworking unit; and releasing the connection between the network of the first type and the network of the second type using an interworking unit.
These and various other advantages and features of novelty which characterize the invention are pointed out with particularity in the claims annexed hereto and form a part hereof. However, for a better understanding of the invention, its advantages, and the objects obtained by its use, reference should be made to the drawings which form a further part hereof, and to accompanying descriptive matter, in which there are illustrated and described specific examples of an apparatus in accordance with the invention.